[ccp4bb] Sulphur SAD at home source

Hi All, I am writing to seek advice on doing sulphur SAD data collection at Cu based home source for a protein that is 12 KDa and has 6 S atoms. I have seen some links online and some references but would be grateful if you can share your know-how for success with this. Like what multiplicity of

Re: [ccp4bb] Sulphur SAD at home source

Well - the S f" is only ~ 0.5 at Cu Kalpha so the signal will be very weak.. Very accurate data may get a solution but you first have to position the S atoms... Much easier to try to make a heavy atom derivative! Eleanor On 3 April 2018 at 15:26, Manoj Saxena < 1d16aa30e8a1-dmarc-requ...@jis

Re: [ccp4bb] Sulphur SAD at home source

Dear Manoj, providing your crystals diffract to at least 2.5 Å and the sulfurs are ordered, you should be able to solve your structure without too many problems. As a first experiment, I would recommend collecting 360 degrees of data. Process these with XDS and the FRIEDEL'S_LAW= FALSE option an

Re: [ccp4bb] Sulphur SAD at home source

Iodine is ideally suited for Cu K-alpha SAD phasing, and iodide ions can normally be easily added by soaking crystals in potassium iodide containing solutions, which can be done at the time of cryopreservation. A quick lit search will turn up the appropriate protocols. For structural genomics w

Re: [ccp4bb] Sulphur SAD at home source

: CCP4 bulletin board On Behalf Of Eleanor Dodson Sent: Tuesday, April 3, 2018 20:17 To: CCP4BB@JISCMAIL.AC.UK Subject: Re: [ccp4bb] Sulphur SAD at home source Well - the S f" is only ~ 0.5 at Cu Kalpha so the signal will be very weak.. Very accurate data may get a solution but you first ha

Re: [ccp4bb] Sulphur SAD at home source

Thank you!, Andreas and all others who replied. I have seen your tutorial and that's what I was referring to. Maybe I can consult you later when I screen some samples and have an idea of signal strength? Regards Manoj 2018-04-03 10:55 GMT-04:00 Andreas Förster : > Dear Manoj, > > providing you

Re: [ccp4bb] Sulphur SAD at home source

separate so that the anomalous differences can be used to find > positions of the S atoms. > > > > Hope that helps, > > Raghu > > > > *From:* CCP4 bulletin board *On Behalf Of *Eleanor > Dodson > *Sent:* Tuesday, April 3, 2018 20:17 > *To:* CCP4BB@JISCMA

Re: [ccp4bb] Sulphur SAD at home source

Dear Manoj, I'm happy to answer your questions and have a look at your data. Maybe we can take this off-list and you report back if and when you solve your structure. By the way, I'm processing native data collected with a MetalJet at the moment. The anomalous signal is even weaker at 1.35 Å bu

Re: [ccp4bb] Sulphur SAD at home source

: Re: [ccp4bb] Sulphur SAD at home source Iodine is ideally suited for Cu K-alpha SAD phasing, and iodide ions can normally be easily added by soaking crystals in potassium iodide containing solutions, which can be done at the time of cryopreservation. A quick lit search will turn up the

Re: [ccp4bb] Sulphur SAD at home source

Hi Manoj, it depends on crystal and hardware (detector, beam, goniometer) quality as well as on the correct strategy whether you will be able to solve the structure with sulfur SAD. 6 sulfur in 12 kDa should be doable, if the crystals diffract to 2.5A or better. Others have given good advice or